Social gaming on Facebook may be past its prime, but don’t tell social gaming juggernaut Zynga that casual gaming is.

The company, which went public late last year, yesterday reported $321m in revenue in the first quarter of 2012 — its highest quarterly revenue figure ever. All told, bookings rose to $329m, up 15% year-over-year, while the $321m in revenue represented a more impressive 32% year-over-year increase.

The numbers handily beat analyst expectations, but it wasn’t all good news for Zynga. Although the company earned some $47m in the quarter on an adjusted basis, increased expenses, some due to stock-based compensation, led to an $85m loss overall. And there were signs that Zynga may have challenges ahead: while monthly active users grew a healthy 24% year-over-year, daily active users were down 6% over the same period.

What matters, of course, is how many players turn to payers, and in that category, Zynga appears to be doing quite alright. Monthly unique payers rose to 3.5m from 2.9m in the past quarter.

Interestingly, the company’s bookings total for the quarter (which measures how many virtual goods Zynga is actually selling) saw the greatest growth from mobile, suggesting that the moves by Zynga competitors like CrowdStar to focus on mobile opportunities are wise indeed. Coupled with the fact that Zynga’s contribution to Facebook’s revenue declined last quarter to 15%, it would appear that Zynga’s finances are starting to reflect the attempts it has been making to reduce its dependence on the world’s largest social network.

That’s obviously good news for Zynga, but as it moves more into mobile and feels the need to spend big to acquire other companies, it will be interesting to see if Zynga can remain social gaming’s top dog.